Gas-powered vehicles are slowly being replaced by vehicles that electrically powered, either partially or wholly. Until now the move to electrically-powered vehicles has been limited to passenger vehicles, but manufacturers like Tesla already have commercial vehicles such as trucks in the works. Some governments have mandated a complete transition to electrically powered vehicles by a certain year.
In electric vehicles, whether partially or fully electric, batteries take up a substantial amount of space in the vehicle platform, meaning that in many cases they cannot be positioned remotely from the passenger compartment. As a result, the batteries are usually put in some sort of sealed enclosure. This ensures that the batteries are protected from water, dirt, and impact from objects hitting the vehicle, and also that the vehicle occupants are protected from unusual events such as leaking batteries or battery overheating.